Articles : JavaBoutique's Introduction to Java : Q and A :

Defining "implementation-dependent"

Q

A

Java uses "interpreted bytecode."

How does Java actually work such that it is implementation-independent? Well that is the cool part. It uses interpreted bytecode.

In Java you write a program in the Java programming language. But when you are done writing, you are not done programming.

Next, you need to translate the Java code (looks like english) into bytecode (looks like gibberish). You do that using a Java Compiler. Once compiled into Java Bytecode, your program can be sent across the net to browsers that have built into them a Java Virtual Machine. A JVM knows how to interpret java bytecode and translate it into the language understood by its host. Thus, a Windows JVMs interprets generic bytecode into Windows machine instructions and a MAC JVM does the same for MAC machine code.

The important point is that the Java programmer is shielded from all of this. She need only write the original Java code and compile it into bytecode. All the implementation dependent stuff happens after she is done! Easy!

There is a good picture of this in the tutorial itself if you go back and check it out.

Selena Sol contributes to the JavaBoutique's Introduction to Java. Selena curently works for Barclays Capital in London, one of the leading global investment banks in Europe and has worked as a software developer for the National Center for Human Genome research, Microline Software, Neuron Data, and Electric Eye in Singapore. Selena is perhaps best-known for creating the Public Domain Web Script Archive (Extropia) and writing several books on Web Programming (Perl, CGI, Java).
Email: selena@extropia.com

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